package com.cobo.fitness.web.calibreapi.mapper;


import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.cobo.fitness.web.calibreapi.entity.Book;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface BookMapper extends BaseMapper<Book> {

    @Select("select author from book where author is not null group by author")
    List<String> queryByAuthor();



}
